Thursday, November 03, 2005

On the design inference

One issue that comes up pretty often in the Intelligent Design debate is: When are we justified in assuming that something is the work of a designer? I was talking with Cory Juhl (who's been talking with resident IDer (yeah, we have one (Rob Koons))), about this today. IDers usually come up with some account involving complexity, and say that the complexity of an object is a sign that it had to be designed by an intelligent agent.

I think it's best to just regard design-inference claims as parts of explanations, and evaluate them the way we generally evaluate explanations. Someone who makes a design inference infers that part of the explanation for some object's existence is that it was generated by a designer. So how would I evaluate this explanation?

First, I'd determine how plausible it was that there existed a designer with the capacities and motives sufficient for creating the object. Then, I'd evaluate this explanation on the usual grounds -- explanatory adequacy / simplicity -- against the best non-design explanations.

I don't know how to properly assess the claim that human beings and other organisms are really amazingly complex. (I don't know what a proper metric for the complexity of an object would look like, and it's up to the IDer to come up with a good one.) But when we start considering explanations including a designer who would have all the right motives to make us, just as we are, and all the weird species in the world, just as they are, we're going to need a terribly non-simple explanation to account for all the data. The designer will have to have all sorts of complex motives and mental states. To quote a Joan Osborne parody from some years back:

What if God smoked cannabis?
Do you suppose He had a buzz
when He made the platypus?
When He created earth our home?
Does He like Pearl Jam or the Stones?

10 comments:

dadahead said...

But when we start considering explanations including a designer who would have all the right motives to make us, just as we are, and all the weird species in the world, just as they are, we're going to need a terribly non-simple explanation to account for all the data. The designer will have to have all sorts of complex motives and mental states.

This part I don't understand. A designer who did all this might be a non-simple entity, but that doesn't mean that the explanation that posits that designer is similarly non-simple, necessarily.

Why would the explanation have to explain why he chose to design everything he did? Seems like that's a different explanation, separate from the claim that there is a designer.

I'm trying to think of an analogy ... say you came across some kind of object, and you couldn't tell if it was a natural object or an artifact. E.g., is it an arrowhead, or just a stone?

It seems like there could be some feature of the object that demonstrated that it was an artifact (was designed) without demonstrating what its purpose was (why it was designed). With the arrowhead example, suppose you didn't know what the hell an arrow even was. But suppose you could tell that the edge had been sharpened. This would tell you that the object had been designed. But you still wouldn't have clue one has to the mindset of the person who designed it.

Anywho, I think the big problem with the 'design inference' is that it is awfully hard to distinguish actual, functional "irreducibility" from us just not knowing at the present time how to explain something in reductive terms. Is that because it cannot be so explained? Or just because we can't presently explain it?

Is there even any way to tell the difference?

Neil Shakespeare said...

You know, this shit isn't even worth talking about, because obviously the "Intelligent Design" folks are just too damn stupid to think. They admit as much. Their whole argument is based on "I'm just too damn dumb to comprehend it". That's all religion is. It's people who have given up on trying to understand. "It's just too complex!" they whine. Meanwhile scientists - who are the ones who TRULY worship existence - search for simplicity. "Simplicty," said Chopin, "is the hardest thing. It is the final thing."

Justin said...

Just a couple thoughts...

You write,

First, I'd determine how plausible it was that there existed a designer with the capacities and motives sufficient for creating the object...

One thing here is that I think that even if you assigned an extraordinarily low prior probability to there being a designer with the appropriate capacities and motives, at least under certain scenarios you would revise that probability in a hurry. Suppose that right now you think there's a 2% chance God exists. Then you walk outside tonight, and you see spelled out in stars up above, "Hey, I'm God. I exist. I spelled this out in stars (!) to convince you of this. That's pretty impressive, no?"

I'm guessing that at that point the fact that you previously thought it's implausible that there is a designer wouldn't prevent you from being awfully convinced in a hurry that there is a god. So, as always, the point can't just be the low prior probability you assign to there being a designer; the point must have a lot to do with you thinking that none of the signs we actually possess (unlike the star message) merits this sort of jump in assigned probability.

Second, I don't really understand the complexity metric either. I feel that there are at least certain understandings of "complex" where I can pretty easily understand horribly complex things that weren't designed. But then I wonder, maybe the argument wouldn't be better served by substituting "designed-ness" for complexity. No doubt, the argument wouldn't be as rhetorically effective then: to start with the premise that human beings exemplify designed-ness seems awfully question begging. But, maybe this is just an appearance. As you touch on, it would be up to a defender of the argument to spell out what designed-ness means and how we assess whether it's being exemplified.

Adam said...

If you have an explanation that invokes a designer, you should know of some designer that actually does the sort of things that you say it does.

Any good historical explanation is based on processes that we know to occur. We know that living systems reproduce and that offspring often have mutations in their DNA. This knowledge is enough to explain the major aspects of life's diversity, but still leaves a lot of details to be explained (and we constantly explain more and more of them). ID doesn't even start to explain the diversity of life because there's no evidence that life is created/altered in the manner that they are suggesting.

Brandon said...

I'm sad to admit how much of the ID arguments I know, but I can say that there is a sort of stand-in for what Justin calls "designed-ness," in contrast to mere complexity (and its near-cousin, "irreducible complexity"). Neo-Creationist William Dembski (who is as sinister and creepy in person as he is in his picture - I saw him speak at UGA when I was an undergrad) uses an analogy to cryptography and the procedures that mathematicians and scientists use to discern "information" from mere randomness in number patterns and so on.

On the face of it, the simple version I gave leaves them open to the obvious objection that cryptographers and mathematicians face a blob of seemingly-random numbers and letters with the assumption that at least SOME of it is genuine information. The same is not necessarily true in the natural world.

But I don't really know the whole story. Dembski claimed (when I saw him) that there is some equation or mathematical formula that is accepted by some scientific community that can be applied to a mish-mash of data and discern whether it was "generated by an intelligence." Dembski claims that DNA (or something like it) generates the "design" flag when you feed it into the formula.

All of this seems profoundly dubious to me, but I can't speak to the science, per se.

I can also tell you that Dembski kicks you off the comments section of his blog, and deletes your comments, if you disagree with him. So in his "professional" life he tries to use a filter to find genuine information, but in his spare time he uses a filter to keep it out.

Jim said...

President Jimmy Carter, quite a religious man, has been appearing every where lately (to sell his book) and he points out that there is nothing wrong with the belief that there was a Designer, capital D. He points out that we cannot put such ideas in a Science class. A true scientist cannot prove ID in the proper scintific manner, so forget it, Kansas school board members!

dadahead said...

I think there's one sense in which the "design inference" isn't totally stupid/crazy.

Consider the physicist who, reflecting on the harmony and order and complexity of the physical universe, comes to the conclusion that there must be a God, that something so beautiful could not be a product of mere chance.

I don't think this is an irrational conclusion to come to. But it is pure speculation, and purely personal. The physicist might include it in his autobiography, but he won't include it in his physics textbook.

Because while it might be reasonable to believe in a "Designer," it's not unreasonable not to - and that's what makes the design inference not a scientific one. Very roughly, it seems like a properly scientific conclusion could be characterized as one which it would be unreasonable or irrational not to believe.

So I don't think anybody who believes in a Designer based on their observation of natural phenomena is crazy. What makes IDers silly is that they falsely believe that the evidence demands the conclusion that a Designer exists, which it most certainly does not.

dadahead said...

My comment above was very poorly written ...

this sentence:

So I don't think anybody who believes in a Designer based on their observation of natural phenomena is crazy.

seems slightly ambiguous - what I mean is that I don't think someone is automatically crazy just because they believe in a Designer, even if they believe it based on certain features of the natural world.

Where IDers go wrong is in thinking that certain features of the natural world prove the existence of a Designer, even if "prove" is meant in a very weak sense.

Neil Sinhababu said...

Dadahead, the complexity of the explanation will depend on how much work the IDer wants it to do. If the IDer wants it to do only a tiny bit of work, that'll weaken his case against evolution, because he can only say then that evolution leaves a little bit of stuff unexplained. If he thinks that evolution can't explain a bunch of stuff and he wants to invoke the designer to explain all of that, he'll have to posit a very intricate set of desires.

If we don't know how to fill out an explanation, but every way of filling it out would posit a whole bunch of entities, that's a problem as far as simplicity goes.

Justin, I agree about the stars scenario.

I took myself to be giving some very general idea of what designed-ness looks like. When something is designed, you can read the intentions of a creator into it.

Adam, my concern with your view is that if faraway aliens send a probe into our solar system and we discover it, we might be able to explain it in terms of a designer, even if we didn't know of its alien creators.

Adam said...

if faraway aliens send a probe into our solar system and we discover it, we might be able to explain it in terms of a designer, even if we didn't know of its alien creators.

I think we may or may not be able to confidently appeal to a creator, depending on the characteristics of the probe. If the probe seemed like something that we could make (size, composition, arangement of parts, inscriptions), then that would increase our confidence that it was designed, especially if there were no competing hypotheses. Of course, if a human could have designed it then the simplest explanation would be that it was actually made by a human.

Also, if we recovered an object drifting in space, we could estimate where it came from based on its trajectory, then make a prediction that we might find something by looking really hard in that region of space... this ability to test the hypothesis that it was designed would at least make it a real scientific theory.

Until we found more information about the hypothesized designers, we'd have to admit that we don't really have any good scientific theory explaining the origin of this object...just like we don't have any good scientific theory about the origin of life (but we do have good theory about how life evolved and diversified after its origins)